#include <iostream>
int sumarrango(int n1,int n2);
using namespace std;
int main()
{
    int n1,n2;
    cin>>n1;
    cin>>n2;
    cout<<sumarrango(n1,n2);
    return 1;

}

int sumarrango(int n1,int n2)
{   int suma;
    suma=0;
    while(n1<=n2)
    {
        suma=suma+n1;
       n1++;

    }
return suma;
}
